Method of increasing the effective radiation of electromagnetic waves.



No. 767,978. 'P-ATENTED AUG. 16, 90

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METHOD OPINGRBASING'ITHE EFFECTIVE RADIATION 0F ELECTROMAGNETIC WAVES.

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No. 767,973. IfATENTBD AUG. 16, 1904.

J.S.STONE. j METHOD OFgINGREASING THE EFFECTIVE RADIATION 0 ELECTROMAGNETIC WAVES.

I 2 APPLICATION FILED OUT. 30, 1903- I0 MODEL. 7 SHEETS-SHEET 2.

Axum U U I No.."7 67,973. PATENTED AUG. 16, 1904.

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METHOD OF INCREASING THE EFFECTIVE RADIATION OP- ELECTROMAGNETIC WAVES..

APPLICATION FILED our. an, 1903.

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METHODOP INCREASING THE EFFECTIVE RADIATION OP ELECTROMAGNETIC WAVES.

APPLICATION I ILED 001230, 1903.

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J. s. STONE" METHOD OF INCREASING THE EFFECTIVE RADIATION 0E ELECTROMAGNETIC WAVES.

APPLICATION FILED 00130, 1903.

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No. 767,973. 7 PAYTENTED AUG; 16, 1904. E J. s. STONE;

METHOD OF INCREASING THE EFFECTIVE RADIATION 0P ELECTROMAGNETIC WAVES.

I APPLIOATION FILED 00130, 1903.

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J.s. sT0NE. I METHQD OF INCREASING T'HE'EFFEGTIVE RADI-JATION OF ELECTROMAGNETIC WAVES.

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I'UNITEI!) STATES Patented August 16, 1904.

PATE T OFFICE."

JOHNSTONE STONE, OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOR TO WILLIAM W. SWAN, TRUSTEE, OF BROOKLINE, MASSACHUSETTS.

METHOD OF INCREASING THE EFFECTIVE RADIATION OF ELECTROMAGNETIC WAVES.

SPECIFICATION formingpart of Letters Patent No. 767,973, dated August 16, 1904. I

Application filed October 30, 1903. Serial No. 179,222. (No model.) I

of Massachusetts, haveinvented certain new and useful Improvements in Methods of Increasing the Effective Radiation of Electromagnetic Waves, of which the following is a specification. I

' My invention relates to the transmission of signals by electromagnetic waves of a kind I that were discovered and investigatedv by Prof.

The properties and characteristics of electromagnetic waves radiated from an elevated.

conductor have long been well known and are clearly set forth in the following publications: Association Fwmeeiis pour lA cemcement cles Sciences, Oompte Renela cle lCl 27 Session,

Nantes, August 11, 1898, part 2, page 212, Prof. A. E. Blondel; Scemces cle lei Sc ciete Frcmcais ele Physique, Paris, May 5, 1899,'2 fascicule, page 48, Dr. Andre Broca; Electrical Review, Vol. 414:, May 5, 1899, London, page 746, Blondel; Electrical Review, Vol. 14:, May'12 and 19,.1899, London, pages 795 and 799, J. E. Taylor; Oomptes Rericlus ales Se'cmees cle lAcaclemie ales Sciences, Tome CXXX, May 21,1900, Paris, page 1383, Blondel. A brief exposition of the theory of the radiation of electromagnetic waves from an elevated conductor is also to be found in the United States Patent No. 706,746, dated August 12, 1902, to which reference is herein made for further information concerning their properties and mode of propagation. tion, howevergis' called to an inaccuracy in the paper hereinbefore referred to read by Blondel beforethe' French Association for the Advancement of Science-win, that currents aredeveloped by electromagnetic waves in a plate of conducting material interposed between the spark-terminals of a Hertz oscillator in the equatorial plane thereof, whereas this plate being in the equatorial-i. e., the equipotentialplane of the oscillator will Attenhave no currents developed therein except such currents as are created therein in'the immediate neighborhood of the oscillator, owing to the fact that the lines of electric force are not everywhere normal to the equatorial plane until a point equal to aquarter-Wave length of the transmitted wave away from the oscillator is reached. Likewise when the elevated conductor is grounded no currents are created in the earth, which is then the equa- ;torial or equipotential plane of the vertical oscillator or elevated conductor except such tric force are not everywhere normal to said surface until the quarter wave length is reached and also owing to the fact that the surface of the earth is not a perfect conductor and except such currents as are created therein when this surface over which the waves travel suddenly changes direction. Attention is further called to an inaccuracy in Patent No. 706,746, in which is repeated the same error which is to be found in the paper above mentioned by J. E. Taylor in the London Electrical Review-viz, that the energy received by a given aerial varies inversely as a given distance, whereas said energy varies inversely as the square of a given distance.

Having thus set forth the bibliography of electromagnetic wave propagation from a grounded elevated conductor and having cautioned those wishing to practice this invention against the errors found in such bibli ography, it will be necessary only to explain in this specification that these waves are radiated by creating electric oscillations in a grounded elevated conductor, preferably ver tically elevated; that theyconsist of two components, one of which (the electric) is normal to the surface of the earth and the other of which (the magnetic) is parallel to the surface of the earth, as set forth in myLettcrsPatent No. 725,634, April li, 1903, and that they travel over the surface of the earth, water, or

other natural media with which said elevated I conductor or transmitting-wire is connected, even although all parts of said surface of 'line.

earth or other natural media in the immediate v1c1n1ty of the base of the transmitting-wire and maintaining said surface in a constantlyconducting state. I have also determined that the area of this surface necessary to be maintained in a more highly conducting condition in order that the radiation may be most efl'ectively increased is the area of a circle whose center is the base of the elevated conductor and whose radius is equal, approximately, to a quarter-wave length of the transmitted wave. It has sometimes been observed that on hot dry days it is impossible to transmit electromagnetic waves from agrounded elevated conductor. I have experimentally determined that this breaking down of a wireless-telegraph transmitting system cannot occur if the natural electrical conductivity of the surface of the earth surrounding the base of the elevated conductor be increased by artificial means and maintained in such state of increased electrical conductivity in the manner described in this specification.

In the drawings which accompany and form a part of this specification, Figure 1 is adiagrammatic illustration of one embodiment of my invention. Figs. 2 to 12 are diagrams hereinafter referred to in explaining the theory of the radiation of electromagnetic waves from anearthed elevated conductor.

In Fig. 1, a is a source of varying electromotive force, which is here shown as an alternating-current generator. in is a key. T is a step-up transformer. C is a condenser. s is a spark-gap. L is an inductance. M is a transformer, preferably a step-up transformer.

V is an elevated conductor or transmitting- Wire. G represents in diagram means whereby the natural radial electrical conductivity of the surface of the earth in the neighborhood of the base of the elevated conductor is increased and maintained in a highly-conducting state.

For the construction of the transmitting apparatus and circuit arrangements and the mode of operation thereof reference may be had to my prior Letters Patent, Nos. 714,756 and 714:, 832, dated December 2, 1902. It is sufiieient to here state that by'means of the apparatus made in accordance with the specifications of said Letters Patent electrical oscillations, which preferably approximate the sinusoidal or simpleharmonic form as closely as practicable, are impressed or forced upon the elevated conductor, either inductively or conductively connected with the sonorous or closed persistently-oscillating circuit M L Cs. However, the transmitting apparatus and circuit arrangements herein shown are merely intended to beillustrative of any transmitting system, and it is to be understood that unless otherwise stated I do not desire my claims to be limited to any particular transmitting system, inasmuch as it is obvious that my invention may be used with any system whereby the radiation of electromagnetic waves is effected.

For making the surface of the earth more highly conducting and maintaining it in a constantly-conducting state a multiplicity of substances may be used. In the drawings 1 have illustrated one embodimentof my invention in which metallic wire-nctting of large mesh, known as chicken-coop netting, is placed in electrical contact with the earth surrounding the lower end of the elevated conductor and is connected to the lower end of said conductor. Such netting has been used successfully for the purpose herein specified. I have also used a layer of conuuercial calcium chlorid, although any other deliquescent salt, which by virtue of its moisture-absorbing properties will maintain the surface of the earth in a constantly-nioistened condition, may be used, and a layer of such salt may with advantage be spread upon the earth within the area covered by the wire-netting. A solution of water and any conducting salt may be used. In fact, I have restored to efficient working order a system by which radiation of electromagnetic waves was ren- 'dered impossible by heat and drought by merely moistening the earth with water for a. distance from the base of the elevated conductor equal approximately to a qrmrter-wave length of the transmitted wave. Iron or other metallic wires disposed radially and circumferentially may be used, and also rocksalt, coarse common salt, charcoal, coke, and, in fact, any substance which exhibits a greater degree of electrical conductivity than the earth. When wire-netting or a system of radially and circumferentially extending metallic wires are so employed, it is to be noted that the effect is virtually a substitution of said netting or metallic wires for the earth as a natural guide for the clectromagnetie waves.

I have discovered that in order to be most eflective for the purpose above specified the means whereby the natural electrical conductivity of the earth or other natural media is increased must extend from the base of the elevated conductor a distance equal approximately to a quarter-wave length of the transmitted wave. The reason for this is that the true radiation of electromagnetic waves does not begin until a point about a quarter-wave length from the elevated conduetmis reached, because it is well known that until this point is reached the electric and magnetic compo nents of an electromagnetic wave are not in lator.

phase and that slight electric currents are created in the earth up to this point.

Although it is indicated by theory that any means employed to increase the natural electrical conductivity of the earth should extend from the base of the elevated conductor a dis';

'tance equal to a quarter-Wave length of the transmitted wave,it is to be distinctly understood that this length is merely the maximum length which may be advantageously employed, while excellent results may be obtained by using a much shorterlength. .Inother words, the area of the netting or system of WiIBS OI other means specified herein may be much smaller than the area of a circle whose radius is equal to a quarter-wave length of the transmitted wave, although better results are. obtained as this area is approximated.

The action of an earthed elevated conductor or vertical oscillator, commonly called the aerial in wireless telegraphy, and the principles involved in the radiation of electromagnetic waves from such elevated conductor or vertical oscillator may more readily be understood by having reference, first, to a Hertz oscillator and, second, to a simple linear oscillator. The principles involved in the radiation of electromagnetic waves from a Hertz oscillator have been set forth by Hertz in a paper entitled The Forces of Electric Oscillations, Treated According to Maxwells Theory, first published in Il 'iedemmms Amm- Zen, Vol. 36, page 1, 1889, and afterward translated by Prof. D. E. Jones and reproduced on pages 136 to 159 of a publication entitled lilectm'c IVrwes, published by Macmil lan & (10., London, 1893. Hertz assumed that an infinitely short oscillator consisting of two spheres connected by a wire had developed therein forced simple harmonic electric oscillations, and upon these assumptions he computed the distribution of electric force aboutthe oscillator for definite times and plotted the distribution of the lines of electric force in the neighborhood of the oscillator for a such times. In Figs. 2 2 2 2 I have represented this distribution of the electric force by a single line in each instance,instead of a plurality of concentric lines, for times t I 0, t fT, t:% T, t=%T,whereTisthehalfperiod of oscillation. Beneath each figure I have represented the potential phase by PP and the current phase by 9 1. At time t I 0 the potential of the oscillator is zero, and this is indicated in Fig. 2 by the absence of lines of force springing from the poles of the osciloscillator and pointing upward indicate the sense in'which the oscillator is about to be charged.- The loops or self-closed lines of electric force represent half-waves that have just been formed. The arrows indicate the direction of the lines of electric force, and At time The two short arrows adjacent to the t I f T, Fig. 2 the potential of theoscillator has increased and lines of force are seen springing from the poles. -At time t f T, Fig. 2, the potential of the oscillator is. at a maximum, and the number of lines of force springing from the poles is therefore a maximum. At time t i T, Fig. 2 the lines of electric force are converging toward the oscillator and are converting their energy into magnetic energy. From this point on a portion of each of the outer lines of force begins -to detach itself from the oscillator as a selfclosed line of force and an equal number of lines of diminished energy sink back into the oscillator until time t T, Fig. 2, when the process is completed and another halfwave is formed. This half-wave would be represented in Fig. 2 by the self-closed lines therein shown with the arrows reversed. A more detailed explanation of the phenomena briefly outlined above is to be found on pages 14:3 to 148 of the paper above referred to in Electric IVcwes. Careful consideration of the diagrams just described and the theory underlying them Will show that in the equatorial along the oscillator is considered. In this connection it may be remarked that inasmuch as Hertz assumed his oscillator to be infinitely short (Electric IVcwes, page 146) his analysis of the oscillator neglected the finite velocity of propagation along the wires connecting the spheres of the oscillator, and therefore the characteristic features of diagrams 3 3 4: 1

- are lost in the diagrams based on his formulae.

Itis also explained that because of this assumption the lines of force in the Hertz diagrams are not continued right up to the representation of the oscillator because his formulae are inadequate in the neighborhood of the finite oscillator shown in his diagrams.

Av simple linear oscillator of finite dimen-' sions impressed with forced simple harmonic electric oscillations is shown in Figs. 3 to 23, inclusive, the phase of the potential being indicated at the base of each figure. In Figs. 3 and 3 A represents a quantity small compared to one-fourth. In Fig. 3 the potential is slightly greater than zero, the arrow parallel to the oscillator indicates the sense in TIC which the oscillator is being charged, and the arrowplaced adjacent to the line of electric the ends of the oscillator. This figure corresponds to Fig. 2'". In Fig. 3 the lines of force parallel to the oscillator is reversed in direction to indicate this change in direction of the moving charge. This figure corresponds to In Fig. 3 -z'. a, at'phase K or time t Tthe two ends of the line of electric force on the oscillator have met at the origin and the electric force has traveled outward a dis- I tance equal to a half-wave length 5 1n the equatorial plane. It will now be noted that the electric force travels outward in the equatorial plane and upward and downward along theoscillator at substantially equal velocities. In Fig. 3 the potential energy of the oscillator is zero and the kinetic energy is a maximum. In Fig. 3 the next half-oscillation is shown as just beginning, the arrow indicating its direction, which is the reverse of that shown in Fig. 3. In these figures it will be observed that again the potential at all parts of the equatorial plane is zero and the magnetic-force is always parallel to the equatorial plane, but that it is not until the quarter-wave length is reached that the electric force is always normal to the equatorial plane. In explanation of this attention is called to the fact that in an oscillator of finite dimensions it is necessary to consider the propagation of the electric force along the oscillator at finite 'line'ff, Fig. 8 and where the velocity becomes equal to the velocity of light. In Fig. 3 the wave thus completely formed at a point equal to a quarter-wave length away from the origin with its magnetic and electric components in phase with respect to time or distance, but in quadrature with respect to space, has proceeded outward a distance equal to an eighth-wave length and the charge on the oscillator has proceeded a distance equal to an eighth-wave length toward the ends of the oscillator and an eighth-wave length outward in the equatorial plane.

The principles involved in the radiation of electromagnetic waves from asimple linear oscillator may be applied to the solution of the earthed elevated conductor or vertical oscillator of wireless telegraphy by the simple expedient of considering the surface of the earth as the equatorial plane of the simple linear oscillator. The actions taking place in the elevated conductor may then be represented by Figs. 4 to 4:, inclusive, and are seen to be identical with those taking place above the equatorial plane in Figs. 3 to 3, respectively. In this case the magnetic force is everywhere parallel to the surface of the earth; but it is not until the quarter-wave length is reached that the electric force is everywhere normal to the surface of the earth, as indicated by the dotted line f" f" in Fig. I. The earth remains at zero -potential throughout, and no currents are developed in it ex cept within the distance equal to a quarterlt wave length A1 from the base of the elevated conductor, as indicated in Figs. 3, 3' I, 4- If the earth be made highly conducting in the immediate vicinity of the oscillator, the currents there developed will not materially change the potential of the earth from ZOIO. If a conductor be placed in the equatorial plane of the linear oscillator-say radially l v and within the distance 1 then by IHgs. 3"

and 3 it will be seen that there is a large component of electric force parallel to the conductor and that equal and opposite currents will be developed upon its upper and lower surfaces. This is indicated in Fig. 12. If the conductor be a perfect conductor, its potential would still be Zero throughout regardless of the current flowing; but it must be of very low conductivity or the current must indeed be excessively great in order to produce an appreciable disturbance of its potential.

In Fig. l2 it will be seen that in the case of an earthed elevated conductor there is likewise a large component of electric force parallel to the surface of the earth and that currents are therefore developed in said surface until a point equal to a quarter-wave length of the transmitted wave away from the base of the elevated conductor is reached, at which point the electric force becomes normal to the surface of the earth and its component parallel to said surface vanishes, and consequent] y the current developed in the earth is reduced to zero. It is therefore apparent that although the currents in the earth are a maximum at the base of the elevated conductor and gradually'- diminish to zero at the quarter-wave length it is not essential that the means described in this application for increasing the natural electrical conductivity of the earth should extend a distance equal to a quarterwave length away from the base of the elevated conductor, and it is for this reason that I have stated in some of my claims that said means should extend outwardly a distance equal approximately to a quarter wave length of the transmitted wave, meaning thereby that such means should extend outwardly a distance sufficiently great for the purpose specified namely-, the purpose of increasing ,four times the length of the grounded oscillator, this being the wave length of the fun' damental of the natural vibrations of such oscillator', whereas with forced vibrations this relation is not essential.

. wave length may be many times the height of the elevated conductor; but this will not necessitate greatly increasing the extent of the artificial ground herein described beyond what it would be for waves four times the height of the vertical.

In the diagrams hereinbefore discussed I have represented the distribution of the electric force about the oscillator in a meridian plane by a single line somewhat approximately representing the direction of the electric force, and I have similarly represented the meridian.

sections of the radiated waves. It will be readily seen, however, that the more complete representation would show many lines approximately concentric with those shown in the diagram. This is most clearly shown by Hertz in his diagrams hereinbefore referred to on pages 144: and 145 of Electric ll cwasgi and this I have indicated in the upper part of Fig. 5, in which are represented in meridian section three' half-waves proceeding outwardly from a ground ed elevated conductor 0. It is to be further'noted that the adjacent lines of electric force of two-adjacent halfwaves are similarly directed and that the lines of magneticforce which are in form concentheir center change their direction with the electric lines.

zero-point but one, as 2.

As indicated in Fig, 5, a wave length is the distance measured radially in the equatorial plane between one zero-point, as to the next The distribution I of the lines of force in the equatorial plane z. a, their density or the number of lines per unit length-determines the shape of the wave. By means of the system described in this application and in my prior patents the shape of the wave is sinusoidalt'. e. the wave is a simple harmonic wave-and therefore the density of the electric force, as well as that The sinusoidal curve between the two parts of Fig- 5 indicates the density of the electric as well as the magnetic force illustrated, respectively, above and below the 'curve at E and M.

At M in Fig. 5 I have shown a portion of the magnetic lines corresponding to the electric lines shown at E. These magnetic llnes.

In such case the are arcs of concentric circles whose center is the oscillator 0. Between 0 and 7F the lines are shown as directed clockwise around O, and between 7F and 2 they are shown as directed counter-clockwise around the oscillator O to correspond with the change of directionof the electric lines and to indicate the polarity of the forces. It will be observed that as the Waves proceed outwardly from the elevated conductor the radius of curvature becomes greater and that at great distances the waves will be practically plane waves because of their great radius of curvature. This is indicated in Fig. 6, which is a representation of the electric lines of the wave shown in Fig. 5

at a great distance from the elevated conductor. The arrows here indicate by the1r d1- rection and length the direction and density of the electric force throughout the wave length.

I have hereinbefore stated that no currents are developed by electroma netic waves in the surface of the earth when an elevated conductor is earthed, except such currents as are developed in said surface in the immedi ate vicinity of the elevated conductor due to .elevated conductor, and I shall now proceed to explain why currents are developed when the said surface deviates from the equatorial plane and why the waves are therebyenabled to passover such obstacles as hills, &c. Consider one of the lines of electric force shown in Fig. 6 meeting an inclined surface. If c, Fig. 7 represents the strength. and direction of the electric force, that component of '0 which is parallel to the inclined surface will be in part absorbed in producing a current in the surface. Suchcurrent in the surface is represented by the arrow 7 If p represents the component of 0) so absorbed, then the vector difference of c and 19 narnely, r

is both diminished in strength and so de-.

more than .a quarter-wave length from the oscillator except in so far as the surface of the earth deviates from the equatorialplane, and there is no reason for assuming that the potential of the earth differs from zero except the air.

for such deviation from the equatorial plane as it may have. In this connection consider Figs. 7, 8, 9, and 10. In Figs. 7 and 8, where the electric force e is directed upward, we see that the current 2' is opposite in sense, owing to the difference in the slope, and it is clear that if there were no slope there would be no current. Similarly, in Figs. 9 and 10, where the electric force o is directed downward, we see that the current 2' is opposite in sense, owing to the difference in the slope, and here again it is clear'that if there were no slope there would be no current. Moreover, it is well known that if a conductor be placed in the equatorial plane of aHertz or linear oscillator 1 at a greater distance than from the oscillator there is no component of electric force parallel to the conductor nor is the conductor cut by any line of magnetic force. There is therefore no tendency to develop a current in said conductor, (see Electric li rwes, page 109;) but if a conductor be placed in the equatorial plane say radially of the linear oscillator and within the distance i-then by Fig.12 we see that there is a large component of the electric force parallel to the conductor and that equal and opposite currents will be developed Whereas heretofore it has been alleged that by means of a construction somewhat similar to that described herein, but in the form of a conducting-strip extending from the transmitting-station in the general direction of the receiving-station, a certain directive effect may be obtained, it is herein pointed out that no such directive effect can be obtained in the manner alleged. In explanation of the foregoing reference is to be had to Huyghens principle, which is applicable to all free waves in an unlimited medium and by which the waves would proceed to spread in all directions as soon as they have passed beyond the limit of the conducting-strip laid upon the earths surface in much the same way that sound-waves proceed to spread in all directions after leaving the end of an organ-pipe, in which they are limited, and passing out into It is not with this alleged directive eflect that this invention is concerned, and I desire it to be understood that 1 here disclaim the use of the invention herein described for such purpose.

Whereas heretofore it has been alleged that by means of a construction somewhat similar to that described herein the capacity and inductance of the vertical transmitting-wire are increased or at least maintained constant irrespective of climatic and other conditions, such as changes of electrical comluctivitv of the surface of the earth in the immediate neighborhood of said transmitting-wire due to salt spray, &c., it is herein pointed out that even when the surface of the earth has the minimum natural conductivity possible under the most unfavorable conditions the capacity of the vertical wire is definite and uninfiuenced by the degree of conductivitv of the surface of the earth for the same reasoir that the capacity of a condenser is uninilnenced by the degree of conductivity of the metal employed for the condenser-plates and that the inductance is completely determined entirely irrespective of the conductivity of the surface of the earth, being dependent solely upon the geometric constants and material of said wire. I therefore desire it to be understood that I here disclaim the use of the invention herein described for such purposes.

An apparatus for carrying out the hereindescribed method has been claimed in my application, Serial No. 179,223, tiled October 30. 1903.

I claii 1. The method of increasing the effective radiation of electromagnetic waves from an elevated conductor, which consi ts in increasing the natural electrical conductivity of the surface of the earth surrounding said conductor for a radial distance equal approximately to a quarter-wave length of the transmitted wave and in maintaining said surface in a constantly-conducting state by artificial means.

2. The method of increasing the effective radiation of electromagnetic waves from an elevated conductor, which consists in increasing the natural electrical conductivity of the surface of the earth surrounding said conductor for a radial distance equal approximately to a quarter-wave length of the transmitted wave and in maintaining said surface in aeonstantly-conducting state by means of a covering of material of greater electrical conductivity than that of said surface.

3. The method of increasing the elt'ective radiation of electromagnetic waves from an elevated conductor, which consists in increasing the natural electrical conductivity of the surface of the earth surrounding said conductor for a radial distance equal a1 proximately to a quarter-wave length of the transmitted wave and in maintaining said surface in a constantly-condnoting state by means of a layer of a deliquescent salt.

4. The method of increasing the effective radiation of electromagnetic waves from an elevated conductor, which consists of artilicially increasing the natural electrical conductivity of the surface of the earth surroumling said conductor for a radial distance equal approximately to a quarter-Wave length of the transmitted wave.

5. The method of increasing the effective radiation of electromagnetic waves from an elevated conductor, Which'consists in substituting for the surface of the earth, as a natural guide for the electromagnetic waves, a metallic netting extending radially from the base of said elevated conductor for a distance equal approximately to a quarter-wave length of the transmitted wave,

6. The'method of increasing the effective radiation of electromagnetic Waves from an elevated conductor, which consists in substituting for the surface of the earth, as a natural guide for the electromagnetic Waves, av

metallic netting and a layer of a deliquescent salt extending radially from the base of said elevated conductor for a distance equal approximately to a quarter-wave length of the transmitted wave.

7. The method. of increasing the effective radiation of electromagnetic waves from an elevated conduct0r, which consists in artifi' 8. The method herein described of increasing the effective radiation of electromagnetic waves from an elevated conductor, which consists in substituting for the surface of the earth, as a natural guide for the electromagnetic waves, a material having greater electrical conductivity than said surface and extending outwardly from the base of said elevated conductor for a distance sufl iciently great for the purpose specified.

In testimony whereof l have hereunto subscribed my name this 30th day of September,

JOHN STONE STONE. Witnesses: BENJ. F. HAINEs, ELLEN B. ToMLINsoN. 

